using System;
using System.Runtime.CompilerServices;
using System.Runtime.ConstrainedExecution;

namespace Foodsoft.Alpm
{
    internal sealed class SafeCachePackageHandle : SafePackageHandle
    {
        internal SafeDatabaseHandle SafeDatabaseHandle
        {
            [ReliabilityContract(Consistency.WillNotCorruptState, Cer.Success)]
            [PrePrepareMethod]
            get;
        } = null!;

        internal SafeAlpmHandle SafeAlpmHandle => SafeDatabaseHandle.SafeAlpmHandle;

        [ReliabilityContract(Consistency.WillNotCorruptState, Cer.MayFail)]
        [PrePrepareMethod]
        internal SafeCachePackageHandle(IntPtr pkgPtr, SafeDatabaseHandle dbHandle)
            : base()
        {
            var success = false;
            RuntimeHelpers.PrepareConstrainedRegions();
            try { }
            finally
            {
                dbHandle.DangerousAddRef(ref success);
                if (success)
                {
                    handle = pkgPtr;
                    SafeDatabaseHandle = dbHandle;
                }
            }

            if (!success) throw new ObjectDisposedException(GetType().FullName);
        }

        [ReliabilityContract(Consistency.WillNotCorruptState, Cer.Success), PrePrepareMethod]
        protected override bool ReleaseHandle()
        {
            SafeDatabaseHandle.DangerousRelease();
            return true;
        }

        public override bool IsInvalid
        {
            [ReliabilityContract(Consistency.WillNotCorruptState, Cer.Success), PrePrepareMethod]
            get => handle == IntPtr.Zero;
        }
    }
}